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  <meta name="Generator" content="EditPlus®">
  <meta name="Author" content="">
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  <meta name="Description" content="">
  <title>Document</title>
	<!--html提供了一个标签，script-->
	<script>
	//标识符规则,字母 下划线 $ 数字(不能用数字开头)
	var a_$2 = 100;
	console.log(a_$2);

	//不能用数字开头
	//var 666abc = 22;
	//console.log(666abc);

	var abc = '哈哈';
	console.log(abc);

	//区分大小写
	//var A = 100;
	//console.log(a); //引用错误，A 和 a 不是同一个变量

	//变量名不能是关键字和保留字
	//var var = 100;
	//console.log(var);//引用错误
	//var class = 100;
	//console.log(class);
	</script>
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